Total knee arthroplasty (TKA) or total knee replacement is a common orthopedic procedure in which damaged or diseased articular cartilage and/or bone of the knee is replaced with prosthetic components. Prior to implanting such prosthetic components, a surgeon generally resects a portion of the patient's native bone in order to shape the bone to receive the prosthetic components. For example, a surgeon might make one or more planar cuts at a distal end of a femur and proximal end of a tibia so that corresponding surfaces of femoral and tibial prosthetic components can be respectively attached thereto.
Each individual cut removal of a section of bone is carefully made. Once native bone is resected from a joint, it is gone forever. In addition, the amount of bone resected and the final geometries of the resected bone significantly influence the fit and alignment of the prosthetic components. Improper fit and/or alignment can result in instability of the joint, increased risk of bone fracture and component failure, pain, and reduced range of motion.
Multiple resection philosophies/techniques have emerged over the years to help ensure proper fit and alignment of the prosthetic components comprising the artificial joint. For example, mechanical axis alignment, anatomic axis alignment, gap balancing, measured resection, anterior referencing, and posterior referencing are some of the various techniques/philosophies that have been widely adopted for forming bone in a TKA procedure.
Surgeons often prefer one technique/philosophy over another. To accommodate surgeon preference, numerous instrument sets have been made available to help guide each cut of a femur and tibia in accordance with a particular technique/philosophy often to the exclusion of other techniques/philosophies. These instruments typically guide a saw blade or other cutting tool to cut a bone at a particular angle and to remove a particular amount of bone. Although, a certain amount of preoperative planning using radiographic images helps a surgeon plan each cut of a joint surface, the actual amount of bone removed and the angle of each cut is often unknown until the TKA procedure is well under way. As such, many instrument sets provide instruments with complicated mechanisms or duplicate instruments that are designed to remove different amounts of bone and guide a cut at different relative angles as needed during the procedure.
The result is that a single manufacturer may provide different sets of instruments for performing the various resection philosophies/techniques with each set including a large quantity of instruments. Prior to a TKA procedure, a surgeon or healthcare facility may order a set of instruments for performing the procedure according to the surgeon's preferred technique/philosophy. These instruments may be stored, sterilized, packaged, and shipped by the manufacturer to the healthcare facility in which the procedure is to take place. In some instances, the instruments may be stored and sterilized at the healthcare facility itself.
The demands of manufacturing, storing, maintaining, sterilizing, packaging, shipping and tracking such a diverse, complicated and large quantity of instruments can be expensive, particularly in a world that is increasingly demanding cheaper surgical procedures. For example, a set of instruments for performing a TKA procedure may cost about 40,000 USD to manufacture. These instruments may then be placed into circulation and are often only provided to a few surgeons who subscribe to the technique/philosophy for which the instrument set was designed. While in circulation, these instruments must be stored, repaired, sterilized, packaged and shipped numerous times over contributing to the overall costs of the instruments. The more instruments provided in each set, the greater the life-cycle costs become, which may reflect back to the cost of the TKA procedure.
Therefore, further improved instruments for use in TKA procedures are desired.